Advanced epoxy resin compositions which have been modified by the in situ formation of the copolymerization product of a vinyl aromatic monomer and minor amounts of a compound containing a group reactive with an epoxide group and a polymerizable ethylenically unsaturated group are taught by Hefner, Jr., et al in copending application Ser No. 790,991 filed Oct. 24, 1985 (Attorney's Docket No. C-34,378). These resins are used to prepare thermosettable powder coatings which when cured (thermoset) provide low gloss, high impact strength coatings. Although excellent cured coatings are provided, the relatively high viscosity per unit epoxide equivalent weight of the modified advanced epoxy resins leads to difficult processability, reduced filler acceptability as well as marginal rheology on curing.
The present invention provides a specific process which results in low gloss, high impact strength epoxy resins with substantially reduced viscosity per unit epoxide equivalent weight and resultant improvements in processability, filler acceptability and rheology.